SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd900ce911201bdc5e7be05ab6396d03a9715045ed2bebc0c72469d02f738562' 
  AND token = 'V7jZiRh2+evj4/JrYV8yMjB6ScRoKSCrgc8uYhz3XF4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}